98 percent of patients across all major HCV genotypes (GT1-6) with
severe chronic kidney disease (CKD), including patients on dialysis,
achieved SVR12 with 12 weeks of G/P in the
primary intent-to-treat analysis, regardless of previous treatment
status or presence of compensated cirrhosis

G/P is an investigational, pan-genotypic, once-daily,
ribavirin-free, fixed-dose combination for the treatment of chronic HCV

G/P includes Enanta’s second protease inhibitor glecaprevir
(ABT-493)

WATERTOWN, Mass.--(BUSINESS WIRE)--Nov. 15, 2016--
Enanta Pharmaceuticals, Inc., (NASDAQ:ENTA), a research and
development-focused biotechnology company dedicated to creating small
molecule drugs for viral infections and liver diseases, today announced
98 percent (n=102/104) of chronic hepatitis C virus (HCV) infected
patients with severe chronic kidney disease (CKD) achieved sustained
virologic response following 12 weeks of treatment (SVR12)
with AbbVie’s investigational, pan-genotypic regimen of glecaprevir
(ABT-493)/pibrentasvir (ABT-530) (G/P) in the primary intent-to-treat
(ITT) analysis. In a modified intent-to-treat (mITT) analysis, SVR12
was achieved in 100 percent (n=102/102) of severe CKD patients.
The mITT analysis excludes patients who did not achieve SVR for reasons
other than virologic failure. These new data from the Phase 3
EXPEDITION-4 study, evaluating patients with chronic HCV infection
across all major genotypes (GT1-6) and severe CKD, will be presented as
a late-breaker today at The Liver Meeting®, the Annual Meeting of the
American Association for the Study of Liver Diseases (AASLD) in Boston.

The EXPEDITION-4 results are the latest to be released from
registrational studies in AbbVie’s G/P clinical development program,
designed to investigate a faster path to virologic cure* for all major
HCV genotypes (GT1-6) and with the goal of addressing areas of continued
unmet need.

Glecaprevir (GLE), an NS3/4A protease inhibitor, is Enanta’s second
protease inhibitor being developed through its collaboration with
AbbVie. G/P is a once-daily regimen that combines two distinct antiviral
agents. G/P is a fixed-dose combination of glecaprevir (300mg) and
pibrentasvir (120mg), an NS5A inhibitor, dosed once-daily as three oral
tablets.

HCV is common among people with severe CKD, reaching prevalence of up to
80 percent in some regions of the world.1 In the U.S., it is
estimated that over 500,000 people have both chronic HCV and CKD2.
Some chronic HCV infected patients with severe CKD, particularly those
with GT2 and GT3 HCV infection, currently don’t have access to
direct-acting antivirals (DAAs). The development of new, safe and
effective regimens to treat HCV in these patients remains a critical
unmet medical need.3

The EXPEDITION-4 study enrolled 104 patients with severe chronic kidney
disease, including 85 patients (82 percent) who were receiving dialysis
at enrollment and 20 patients (19 percent) who had compensated
cirrhosis. The study also included those who were not cured with
previous treatment with sofosbuvir (SOF) plus ribavirin (RBV) or with
interferon (IFN) plus RBV, with or without SOF (44 patients, 42 percent).

The majority of treatment related adverse events (AEs) were mild or
moderate. The most commonly reported AEs included pruritus, fatigue and
nausea. Of the 24 percent of patients who experienced serious AEs, none
were considered related to G/P. Four AEs (4 percent) led to the
discontinuation of G/P and one patient died after achieving SVR4
due to a serious AE (intracerebral hemorrhage) considered not-related to
G/P.

*Patients who achieve a sustained virologic response at 12 weeks post
treatment (SVR12) are considered cured of
hepatitis C

About the EXPEDITION-4 StudyEXPEDITION-4 is a single-arm,
open-label, Phase 3 study evaluating the safety and efficacy of 12 weeks
of G/P in patients with GT1-6 chronic HCV infection and chronic kidney
disease, including those on dialysis. The primary endpoint is SVR12.

Patients in the study had severe or end stage kidney disease (stage 4
and 5 CKD), with an eGFR < 30 mL/min/1.73 m2 required at screening.
Prior treatment in the study is defined as treatment with interferon
(IFN)/pegIFN ± RBV, or sofosbuvir (SOF) + RBV ± pegIFN therapy.

About EnantaEnanta Pharmaceuticals is a research and
development-focused biotechnology company that uses its robust
chemistry-driven approach and drug discovery capabilities to create
small molecule drugs for viral infections and liver diseases. Enanta’s
research and development efforts are currently focused on four disease
targets: Hepatitis C Virus (HCV), Hepatitis B Virus (HBV), Non-alcoholic
Steatohepatitis (NASH) and Respiratory Syncytial Virus (RSV).

Enanta has discovered novel protease inhibitors that are members of the
direct-acting-antiviral (DAA) inhibitor classes designed for use against
the hepatitis C virus (HCV). These protease inhibitors, developed
through Enanta’s collaboration with AbbVie, include paritaprevir, which
is contained in AbbVie’s marketed DAA regimens for HCV, and glecaprevir
(ABT-493), Enanta’s second protease inhibitor product, which AbbVie has
developed in Phase 3 studies in a fixed-dose combination (G/P) with
pibrentasvir (ABT-530), AbbVie’s second NS5A inhibitor, and is preparing
for regulatory approval filings in the U.S., Europe and Japan.

Enanta has also discovered EDP-305, an FXR agonist product candidate for
NASH, currently in Phase 1 clinical development, as well as a
cyclophilin inhibitor, EDP-494, a novel host-targeting mechanism for
HCV, which is also in Phase 1 clinical development. In addition, Enanta
has early lead candidates for HBV and RSV in preclinical development.
Please visit www.enanta.com
for more information on Enanta’s programs and pipeline.

Forward Looking Statements Disclaimer

This press release contains forward-looking statements, including
statements with respect to the prospects for AbbVie’s investigational
HCV treatment regimen containing glecaprevir (ABT-493). Statements that
are not historical facts are based on management’s current expectations,
estimates, forecasts and projections about Enanta’s business and the
industry in which it operates and management’s beliefs and assumptions.
The statements contained in this release are not guarantees of future
performance and involve certain risks, uncertainties and assumptions,
which are difficult to predict. Therefore, actual outcomes and results
may differ materially from what is expressed in such forward-looking
statements. Important factors and risks that may affect actual results
include: the efforts of AbbVie (our collaborator developing glecaprevir)
to develop its glecaprevir/pibrentasvir(G/P) combination and
successfully obtain regulatory approval and commercialize it; the
regulatory and marketing efforts of others with respect to competitive
treatment regimens for HCV; regulatory and reimbursement actions
affecting G/P, any competitive regimen, or both; the need to obtain and
maintain patent protection for glecaprevir and avoid potential
infringement of the intellectual property rights of others; and other
risk factors described or referred to in “Risk Factors” in Enanta’s most
recent Form 10-K for the fiscal year ended September 30, 2015 and other
periodic reports filed more recently with the Securities and Exchange
Commission. Enanta cautions investors not to place undue reliance on the
forward-looking statements contained in this release. These statements
speak only as of the date of this release, and Enanta undertakes no
obligation to update or revise these statements, except as may be
required by law.